alive by ambulance. unlike his brother his alleged co-conspirator in monday deadly attack tamerlan tsarnaev, they were tra tracked down last tonight after police said pair ambushed mit officers shawn collier fatally shooting him in pa control tar and hijacked this suv andñr wild khis throwig explosives. they canvas the neighborhood going door to door more than 1 million resident were put on lock down. but tonight this city and this nation rest a bit easier. >> we have closed an important chapter in this tragedy. >>reporter: suspect hop laced tonight. still don't know the full accident of his injuries or the motive. life in watertown, massachusetts, abc news. now become to you. >> marsy thank you. when this all unfolded tonight in watertown our amma right there. she heard the shots and watched police jump in action. the mood is celebration amma? >> certainly is but as you said tense for a short time. when we heard the gun fire but as soon as people here learn that that suspect had been captured it was quite a celebration. just take a look as people rushed in to the streets.